Protective fuse structures for transformers



1956 P. w. MUSCHONG 2,773,152

PROTECTIVE FUSE STRUCTURES FOR TRANSFORMERS Filed June 18, 1952 INVENTOR. PETER W. MUSCHONG ATTORNEY BY; i

United States Patent 6 PROTECTIVE FUSE STRUCTURES FOR TRANSFORMERS Peter W. Muschong, St. Louis, Mo., assignor to Moloney Electric Company, St. Louis, Mo., a corporation of Delaware Application June 18, 1952, Serial No. 294,223

7 Claims. (Cl. 200133) This invention relates generally to protective means for transformers and more specifically to an improved structure adapted to have associated therewith a protective fuse link which is arranged in series with the high voltage leads of a transformer so as to provide internal protection for the transformer, the predominant object of the invention being to provide such a protective means which is easily and readily replaced as a unit, in the event of outage, and which is so constructed and arranged as to adequately insulate the fuse link and a lead connected thereto from ground or other adjacent parts of the transformer.

Fig. l is a fragmentary plan view of a transformer showing one of the improved fuse structures of this invention associated therewith.

Fig. 2 is a fragmentary side elevation of a transformer portion with one of the improved fuse structures of this invention mounted thereon.

Fig. 3 is an elevation illustrating a portion of a transformer with the improved fuse structure of this invention associated therewith.

Fig. 4 is an enlarged section taken on line 44 of Fig. 1.

Fig. is a fragmentary view partly in vertical section and partly in elevation illustrating the improved fuse structure of this invention.

Fig. 6 is an inverted, fragmentary view of the structure shown in Fig. 5.

Fig. 7 is a perspective view of a bracket member forming an important part of the fuse structure of this invention.

The protective fuse structure A of this invention includes a bracket member 1 which is formed of a good electrical insulating material, for instance, phenolic resin possessing high impact and dielectric strength.

By referring particularly to Fig. 7 of the drawing it will be noted that the bracket member 1 is provided with an integral extension 2 that has a tapered opening 3 formed therethrough, said opening being extended entirely through said extension and said extension being provided with a recess 3' formed therein at one end of the opening 3 which is of greater diameter than said opening. The bracket member 1 is provided with portions 4 and 5 that extend in opposite directions from the extension 2, said portions 4 and 5 being of arcuate cross-sectional shape to provide an elongated channel or opening 6 that extends continuously from the outer end of the portion 4 to the outer end of the portion 5, and longitudinally extended spaces 4' and 5 defined by the interior walls of the portions 4 and 5. Also, the portion 4 of the bracket member 1 is provided with opposed, flattened parts 7 which are formed in the wall thereof in horizontal alinement and an opening 8 is formed through the wall of said portion 4 from one flattened part to the other, the curvature of the wall of said portion 4 causing a portion of the opening 8 to produce a curved slot 9 in the inner face of the wall of said portion 4.

The bracket member 1 of the structure of the present "ice invention is shown as being supported by a terminal block T of a transformer T with which the improved fuse structure A is associated, said terminal block having a pair of opposed bosses or tapered extensions Ta one of which is received in the tapered opening 3 of the extension 2, as is shown to good advantage in Fig. 5, and being supported from the frame of the transformer T by the element Tb. The terminal block T has an opening T formed therethrough which extends from the outer face of one of the tapered extensions Ta to the outer face of the other tapered extension Ta, and extended through said opening and projected beyond the opposite ends thereof is a stud 10. One projected end portion of the stud 10 is screwthreaded While the opposite end portion thereof is provided with a recess 11 which receives an end portion of a conductor Ca, the recessed end portion of the stud being crimped about the end portion of the conductor located in the recess so as to securely connect said stud and conductor electrically and mechanically. The stud 10 is provided with a knurled portion 12 which which serves to provide for secure attachment of the stud with respect to the face of the opening T". The stud 10 is provided with a collar 13 which is disposed in a recess 14 formed in a portion of one tapered portion Ta of the terminal block of the transformer T, and, also, the screwthreaded end portion of the stud 10 extends through an opening 15 formed in a portion 15a of a terminal lug 15, with a nut 16, which is screwthreadedly mounted on the screwthreaded end portion of the stud, tightly engaging a face of said terminal lug portion 15a so as to firmly secure said terminal lug to said lug mechanically and electrically, said not 16 serving as the sole means for securing the unit made up of said bracket member, said terminal lug, and fuse assembly in place. The terminal lug portion 15:: is disposed substantially horizontal and said terminal lug includes also a substantially vertical portion 15b to which is mechanically and electrically attached an end portion of a conductor Cb.

Disposed in the opening 6 of the bracket member 1 is a fuse 17 comprising a tubular element 18 through which is extended a fusible fuse link 19, and the conductor Cb, previously mentioned herein as being attached to the terminal lug 15 at one end thereof, is mechanically and electrically attached at its opposite end portion to said fuse link 19. The fuse 17 is maintained in its proper position in the opening 6 of the bracket member 1 through the instrumentality of a pin 20 which is supported in the opening 8 of the bracket member 1, a part of said pin 20 being projected outwardly beyond the curved slot 9 of said bracket member and this part of said pin being seated in a part of an annular groove 21 formed in the outer face of the tubular element 18 of the fuse 17, as is shown in Fig. 5. Thus, the fuse 17 is prevented by the pin 20 from moving longitudinally of its major axis with respect to the bracket member 1, yet said fuse may be readily removed for replacement by merely driving the pin 20 from the opening 8. The fuse link 19 adjacent to its upper end has associated therewith a bolt 22 which serves to mechanically and electrically attach a conductor Cc thereto, this conductor extending to the bushing of the transformer with which the improved fuse structure is associated.

When, in the use of the improved protective fuse structure of the present invention, the fuse link 19 thereof is ruptured and it is desired to replace said ruptured fuse link with an intact fuse link, it is necessary, merely, to detach the conductor Cc from the upper portion of the ruptured fuse link. This being done the nut 16 is unscrewed from the upper screwthreaded end portion of the stud 10, and because said nut 16 is the sole means for securing in place the entire fuse assembly comprising the bracket member 1, the terminal lug 15, the conductor Cb,

and the fuse 17 is removed as a unit and is replaced by a renewal unit comprising the same parts but with an intact.

fuse link 19. The conductor Cc is then connected to the fuse link with the aid of the bolt 22 and the nut 16 is replaced on the screwthreaded end portion 'of the stud 10 and drawn tight to secure the renewal unit in place. It is to be noted that the terminal lug 15 is so arranged and positioned with respect to the lower end portion of the fuse link 19 that the conductor Cb may not accidentally contact adjacent parts of the transformer or tank thereof. Also, the portion 5 of the bracket member 1 serves as a protective skirt that extends below the lower end of the fuse link and thereby provides insulation between the location of the protective fuse structure A and the tank or frame of the transformer with which said protective fuse structure is associated.

I claim:

1. In a fuse-protected transformer, a terminal block affixed to said transformer and having a boss thereon, a fuse assembly comprising a mounting bracket carrying a fuse, said' bracket having an extension provided with an opening to receive said boss, a stud projecting from said boss and extending through said opening, a terminal lug electrically connected to said fuse by a conductor, said terminal lug adapted for electrical and mechanical engagement with said stud, and a removable fastener for securing the terminal lug to the stud and securing the extension on said boss whereby the fuse assembly can be replaced as a unit by removal of said fastener.

2. Apparatus as set forth in claim 1 in which said electrical conductor is flexible.

3. Apparatus as set forth in claim 1 in which the stud extension is screw-threaded and said fastener comprises a nut.

4. Apparatus as set forth in claim 1 in which said mounting bracket includes a channel in which said fuse is slidably engaged.

5. Apparatus as set forth in claim 1 in which said mounting bracket includes a channel adapted to substantially encompass said fuse and in which said fuse is slidably engaged, and means for retaining said fuse in a fixed relationship with said bracket channel.

6. Apparatus as set forth in claim 5 in which said electrical conductor is flexible, and in which said stud extension is screw-threaded, and said fastener comprises a nut.

7. In a fuse protected transformer, a terminal block affixed to said transformer and having a boss projecting from one face thereof with an opening through the block and the boss, a terminal stud received in said opening projecting from the boss and having a threaded end portion outward of the boss, a bracket mounted on said face of the block and having an opening receiving said boss, said bracket having a second opening extending parallel to said first-mentioned opening and located outward of the block for removable reception of a fuse, said fuse having a flexible conductor adapted for electricalconnection at one end of said stud, and removable nut means threaded on the stud holding said one end of the conductor in electrical contact with said stud.

References Cited in the file of this patent UNITED STATES PATENTS McGlothlen Oct. 27, 1953 

